Subjects with histories of moderate alcohol use are studied on the Residential Research Unit to assess the effects of ethanol following pretreatment with neither acetaminophen (325, 650, 1300 and 1950 mg) or placebo. Acetaminophen is a prostaglandin synthetase inhibitor that has been shown to reduce several behavioral and physiologic effects of alcohol in animal studies, alcohol appears to act in part by increasing prostaglandin levels. This drug interaction study makes use of our standard procedures for assessing abuse potential and performance to evalate the possibility of such antagonistic effects in human subjects. This study is conducted in collaboration with the Preclinical Branch. Subject testing has been completed. Preliminary analyses indicate that alcohol at this dosage (0.625 gm/kg, taken over 90 mins) caused subjective effects (drunk, feel drug, sober, etc) but did not reliably change physiologic or performance measures. Pretreatment with acetaminophen did not influence the subjective effects. The results are submitted for publication.